<template>
  <div>
    <router-link tag="div" to="/" class="header-abs" v-show="showAbs">
      <div class="iconfont head-abs-back">&#xe624;</div>
    </router-link>
    <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  methods: {
    handleScroll () {
      const top = document.documentElement.scrollTop
      if (top > 60) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = {
          opacity: opacity
        }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  },
  created () {
    window.addEventListener('scroll', this.handleScroll)
  },
  beforeDestroy () {
    window.removeEventListener('scroll', this.handleScroll)
  }
}
</script>

<style lang="stylus" scoped>
@import '~@/assets/styles/varibles.styl'
.header-abs
  position:absolute
  left:.2rem
  top:.2rem
  width:.8rem
  height 0.8rem
  background:rgba(9,9,9,.8)
  border-radius:50%
  line-height:.8rem
  text-align:center
  .head-abs-back
    color:#fff
    font-size:.4rem
.header-fixed
  position:fixed
  top:0
  left:0
  right:0
  color:#fff
  height:$headerHeight
  line-height:$headerHeight
  text-align:center
  background:$bgColor
  font-size:.32rem
  z-index:2
  .header-fixed-back
    width:.64rem
    text-align:center
    font-size:.4rem
    position:absolute
    top:0
    left:0
    color:#fff
</style>
